High Pressure Bridgman Grown CdZnTe for Electro-optic Applications

High Pressure Brisgman ( HPB) grown CdZnTe uis employed ofr X and gamma-rays detectors. Recently, it has been demonstrated that HPB CdZnTe crystals can be efficiently used for subnanosecond all-optical switching in the thirs telecommunication range. On the other side, high resistivity CdTe:In crystals have been used since long as electro-optic mopdulators at 1o um, according to their high electro-optic figure of merit. Unfortunetaly the exploitation of CdTe:In crystals for electro-optic device s in the near IR is inhibited by the space charge effect due to photogenerated carriers that shield , at low modulation frequencies, the effect of the external field. In this work we demonstrate that HPB CdZnTe cystals do not exibit the space charge effect in the whole third telecommunication range of wavelength, due to CD operation and for an optical power up to few milliwatts. The absence of shield is surprisingly, as optical absorption around 1.5um is slightly higher in CdZnTe cystals and could be sttributed to the presence of an efficient recombination center. Two crystals were inserted inside a 2 x 2 electro-optic switch, in a polarization-diversity configuration, demonstrating a -27dB cross talk performance.